Fluid operated pump system with external pump passages



Feb. 26, 1963v R F MCAPRTHUR ET AL 3,078,804

FLUID OPERATED PUMP SYSTEM WITH EXTERNAL PUMP PASSAGES Filed June 8, 1959 4 Sheets-Sheet 1 4 Sheets-Sheet 2 R. F. MCARTHUR ET AL FLUID OPERATED PUMP SYSTEM WITH EXTERNAL PUMP PASSAGES ,MA man/6A?. MEQ/5M 5y F15/1 rrae/vfy ,H2/ems; Mec@ Rassen. Kee/v.

Feb. 26, 1963 Filed June 8, 1959 Feb. 26, 1963 R. F. MCARTHUR ETAL 3,078,804

FLUID OPERATED PUMP SYSTEM WITH EXTERNAL PUMP PASSAGES 5419x403, ,MH THE MEC 4 Sheets-Sheet 5 Feb- 26, 1963 R. F. MCARTHUR ET AL 3,078,804

FLUID oPERATED PUMP sysTEM WITH EXTERNAL PUMP PAssAGEs Filed Jue 8, 1959 4 Sheets-Sheet 4 ,Mn men/ Mesas/E lBy 77151,? 4mm/sys. ,fmQ/S, lr6/Echi, Rassen.

3,078,864 FLUlD GPERATED PUMP SYSTEM WITH EXTERNAL PUMP PASSAGES Ralph F. McArthur, Huntington Parli, and Mathew R.

Mecusirer, La Habra, Calif., assignors to Kobe, Inc.,

Huntington Parli, Calif., a corporation ot California Filed .lune 8, 1959, Ser. No. 318,2;70 1t) Claims. (Cl. MP3-4) The present invention relates in general to iiuid op erated pump systems for wells, such as oil wells, and more particularly, to a pump system comprising an elongated, fluid operated pump or pump assembly of the reciprocating type having an engine or motor means which is operable by a liuid, such as oil, under high pressure to actuate a pump means, consisting of one or more pump sections, tor pumping production fluid from he well to the surface, a primary object of the invention being to provide the pump means of such a pump assembly with the maximum possible displacement for a given diameter,

As general background, the invention contemplates a iluid operated pump assembly having a motor means or motor section which includes an engine or motor piston reciprocable in its cylinder by an alternating operating uid pressure force differential applied thereto under the control of an engine or rotor valve. The pump assembly includes at least one pump cylinder having therein a pump piston connected to the motor piston and reciprocable thereby to pump production fluid from the Well to the surface, suitable inlet and outlet valves controlling the admission and discharge of pro-duction tluid.

The invention further contemplates a iluid operated pump assembly requiring Le admission and/or discharge of huid at interconnected vertically spaced points and, ni re particularly, a pump assembly having an engine r motor means requiring the admission and/ or discharge of operating iiuid at interconnected vertically spaced points, and having a pump means requiring the admission and/or discharge of production fluid at interconnected vertically spaced points. This latter condition may be present with various pump means incorpo-rated in the pump assembly. For example, the pump means may comprise one double-acting pump or pump section requiring admission and discharge of production lluid at the upper and lower ends of the pump cylinder thereof. Alternatively, the pump means may include two o-r more pump sections in tandem, the pump cylinders of such a pump means requiring admission and discharge of production fluid at at least two vertically spaced points in the event that the pump sections are single acting, and requiring admission and discharge or" production iluid at a plurality of vertically spaced points in the event that the pump sections are double acting.

An object of the invention of prime importance is to provide a pump assembly having at least two vertically spaced ports for the admission or discharge of operating or production iluid and to provide a bottom hole assembly adapted to receive the pump assembly in an operative position therein and having fluid passage means externally of the pump assembly for interconnecting the aforementioned ports in iluid communication when the pump assembly is in its operative position.

More particularly, an important object of the invention is to provide a pump assembly including motor means having at least two vertically spaced ports for the admission or discharge of operating iluid and to provide a bottom hole assembly adapted. to receive the pump assembly in an operative position therein and' having operating fluid passage means externally of the pump assembly for interconnecting the aforementioned Patented Feb. 26, 1963 2 operating fluid ports in iluid communication when the pump assembly is in its operative position.

Sttill more particularly, another important object of the invention is to provide a pump `assembly including pump means having at least two vertically spaced ports for the admission or discharge of production lfluid and to provide a bottom hole assembly adapted to receive the pump assembly in an operative position therein Iand having production iluid passage means externally of the pump assembly for interconnecting the aforementioned production fluid ports in fluid communication when the pump assembly is in its operative position.

Another object ot the invention is to provide a fluid operated pump system for a well which includes a pump assembly comprising pump means having two vertically spaced production uid inlets for production fluid from the well and two vertically spaced production iluid outlets for production liuid discharged by the pump means, and which includes a bottom hole assembly adapted to receive the pump assembly in an operative position therein and having production inlet passage means and production outlet passage means externally of the pump assembly for interconnecting the production fluid inlet in fluid communication and for interconnecting the production fluid outlet in lluid communication, respectively, when the pump assembly is in its operative position.

The important thing about the foregoing construction is that the various passage means which interconnect the 4operating lluid ports and the production fluid inlets and outlets are formed in the bottom hole assembly externally of the pump assembly, and not in the pump assembly itself. Consequently, the passage means in question do not take up part of the cross sectional varea of the pump assembly, which means that the maximum possible proportion of the cross sectional area of the pump assembly can be utilized for the motor cylinder and for the pump cylinder or cylinders. Consequently, the pump assembly is provided with the maximum possible displacement or a given over-all diameter of the pump assembly.

Considering the importance of ylocating various passage Ine-ans associated with the pump `assembly in the bottom hole assembly externally of the pump assembly, this permits an increase in the diameter of the pump cylinder or cylinders, and a corresponding increase in the diameter of the engine cylinder, suiiicient to double the capacity or displacement of the pump assembly for a given overaall diameter. Looked at from another point of View, the present invention pnovides a pump assembly having `a minimum over-all diameter for a given dis-placement. Aside from the economies resulting directly from minimizing the diameter of the pump assembly for a given displacement, the present invention results in substantial reductions in tubing costs in a so-called free pump system wherein the pump assembly is movable between the surface and its operative position in the bottom hole assembly through` a pump tubing set in the well. As will be apparent, since the invention achieves a given `displacement with a minimum pumpessembly diameter, the diameter of the pump tubing is minimized also with substantial savings in tubing costs.

Another object of the invention is to provide a fluid :operated pump system wherein the external operating iiuid passage means which interconnects vertically spaced ports in the engine means of the pum-p assembly includes an annular passage encircling the pump assembly and having inner and outer walls respectively deiined by the pump assembly and the bottom hole assembly when the pump assembly is in its operative position.

A further object of the invention is to provide a lluid Operated pump system wherein at least one of the external production fluid passage means which interconnects vertically spaced por-ts in the pump means of the pump assembly includes an annular passage encircling the pump assembly and having inner and outer walls respectively defined by the pump assembly and the bottom hole assembly when the pump assembly is in its operative position. A further object in this connection is to provide a pump system wherein the annular passage just mentioned forms part of the production duid inlet passage means interconnecting the vertically spaced production fluid inlets of the pump means.

Another object of the invention is to provide a pump assembly which includes a single engine section and two double-acting pump sections structurally connected in tandem, the pump assembly including an upper sealing adapter at the upper end of the motor section havingr thereon external sealing means engageable with an upper sealing collar on the bottom hole assembly, an upper intermediate sealing adapter intermediate the motor section and the uppermost of the pump sections having thereon external sealing means engageable with an upper intermediate sealing collar on the bottom hole assembly, a lower intermediate sealing adapter between the pump sections having thereon external sealing means engageable with a lower intermediate sealing collar on the bottom hole assembly, and a lower sealing adapter at the lower end of the lowermost of the pump sections having thereon external sealings means engageable with a lower Sealing collar on the bottom hole assembly. The Various external sealing means carried by the sealing adapters mentioned prevent intermingling of the operating fiuid under pressure for actuating the motor section, the spent operating fluid discharged by the motor section, the production uid from the well admitted to the pump sections, and the production iiuid discharged by the pump sections.

A further object is to provide a pump system of the foregoing nature wherein the external production iiuid inlet passage means includes two vertically spaced, annular passages encircling the pump assembly respectively above and below the lower intermediate sealing adapter and collar when the pump assembly is in its operative position, and respectively communicating with the production uid inlets of the two pump sections.

Another and important object of the invention is to provide a pump assembly having thereon external sealing means engageable with the bottom hole assembly and including elastomeric annular seals which are constantly in' states of compression when the pump assembly is in its operative position.

Another object is to provide a pump assembly wherein each elastomeric annular seal is maintained in a state of compression by constantly applying thereto a pressure force which produces a pressure within the seal greater than any fluctuating iiuid pressure differential to which it may be subjected during operation of the pump assembly.

With the foregoing construction, the elastomeric annular seals are prevented from expanding and contracting excessively in response to the application of fluctuating fluid pressure force differentials thereto during the operation of the pump assem ly, thereby minimizing internal friction within the seals and thereby preventing the detrimental heat generation which would otherwise result.

A further object of the invention is to provide means for loading each elastomeric annular seal which comprises a differential-area sleeve engageable with the seal and exposed to suitable fluid pressures associated with the pump assembly.

The foregoing objects, advantages, features and results of the present invention, together with various other objects, advantages, features and results thereof which will be evident to those skilled in the fluid operated pump ar-t, may be achieved with the exemplary embodiments of 4 the invention described in detail hereinafter and illustrated in the accompanying drawings, in which:

FIG. l is a vertical sectional view illustrating diagrammatically a fluid operated pump system which embodies the invention as installed in a Well, this pump system being illustrated in specific detail throughout the remainder of the drawings;

lFIG. 2 is a vertical sectional view of the upper end of the fluid operated pump system of the invention shown in specific detail, and is taken as indicated by the arrowed line 2 2 of FIG. 7;

FIG. 3 is a vertical sectional view of a portion of the pump system below that illustrated in FIG. 2 and is taken along the arrowed line 3 3 of FIG. 8;

FIG. 4 is a vertical sectional view of a portion of the pump system below that illustrated in FIG. 3 and is taken as indicated by the arrowed line 4 4 of FIG. 9;

FIG. 5 is a vertical sectional view of a portion of the pump system below that of FIG. 4;

FIG. 6 is a vertical sectional view of the lower end of the pump system;

FIGS. 7, 8 and 9 are horizontal sectional views respectively taken along the arrowed lines 7 7, 8 8 and 9 9 of FIGS. 2, 3 and 4, respectively; and

FIGS. 10 and 1l are enlarged, fragmentary vertical sectional views illustrating seal loading means of the invention in more detail.

Referring particularly to FIG. 1 of the drawings, the fluid operated pump system of the invention includes a bottom hole assembly 2t) which provides a housing means for receiving and housing in an operative position therein a free, fluid operated pump assembly 22. The bottom hole assembly 20 is suspended in a well casing 24 provided at its lower end with a perforated liner 26, shown as integral with the casing, through which production fluid from a surrounding productive formation 28 may enter the well. The suspension means for the bottom hole assembly 20 comprises a tubing system which includes a supply tubing 30 for delivering an operating fluid under pressure to the pump assembly 22 when it is in its operative position in the bottom hole assembly, a return tubing 32 for conveying spent operating iluid from the pump assembly to the surface, and a production tubing 34 for conveying to the surface production fluid from the well which is discharged by the pump assembly. The free pump assembly 22 is hydraulically movable between its operative position in the bottom hole assembly 20 and the surface through the supply tubing 30 in the construction illustrated.

It will be understood that while a separate return tubing 32 for the spent operating fluid has been disclosed, thereby providing a closed operating fluid system, the spent operating fluid may be mixed with the production fiuid and returned via the production tubing 34, thereby providing an open operating fluid system.

Considering the bottom hole assembly 20 in a general way, and primarily with reference to FIG. 1 of the drawings, it includes an upper sealing collar 36 to which the lower ends of the supply and return tubings 30 and 32 are connected. As will be described in more detail hereinafter, the upper sealing collar 36 provides an operating fluid exhaust passage means 3S which conveys spent operating fluid from the pump assembly 22 to the return tubing 32.

Connected to the lower end of the upper sealing collar 36 is the upper end of a motor housing tube 40 to the lower end of which is connected an upper intermediate sealing collar 42. The lower end of the production tubing 34 is connected to the sealing collar 42 and this sealing collar is provided with a branch outlet passage means 44 which conveys production fluid discharged by the pump assembly 22 to a main outlet passage means 46 for production uid which leads to the lower end of the production tubing 34.

Connected to the lower end of the upper intermediate` sealing collar 42 is the upper end of an upper pump housing tube 4S to the lower end of which is connected a lower intermediate sealing collar Si) having th-erein a branch outlet passage means 52 which conveys production lfluid discharged by the pump assembly 22 to the main out- Ilet passage means 46.

rthe lower end of the lower intermediate sealing collar 50 has connected thereto the upper end of a lower pump housing tube and connected to the lower end of this tube is a lower sealing collar S5 having a bottom shoe S6 connected thereto. Formed in the bottom shoe 56 is a branch outlet passage means 5S which conveys production uid discharged by the pump assembly 22 to the main outlet passage means 46.

The supply tubing Sii, the sealing collars Sti, 42, Sil and 5S, the motor housing tube 4), the pump housing tubes i3 and 54, and the bottom shoe 56 are all axially, i.e., vertically, aligned and provide a housing or housing means for the pump assembly 22, the latter being movable between the surface and an operative position within the bottom hole assembly 2d through the supply tubing. The bottom shoe Se is provided therein with an annular seat et) for a standing valve assembly 62 on which the lower end of the pump assembly 22 is seated when the pump assembly is in its operative position in the bottom hole assembly.

The standing valve assembly communicates with the interior of the perforated liner 26 and constitutes the lower end of a production iiuid inlet passage means 64 for conveying production iiuid from the well to the pump assembly 22, for pumping into the main outlet passage means 46 by way of the branch outlet passage means 44, 52, and 5S. The inlet passage means de includes, generally, an inlet passage 66 formed in an inlet plug 68 and a lower sealing adapter 151i of the pump assembly 22, by the inlet plug forming the lower end of the pump assembly and being seated on the standing valve assembly 62 when the pump assembly is in its operative position in the bottom hole assembly 2li. The inlet passage means 64 also includes a lower annular passage 7@ the lower end of which communicates with the inlet passage ed, the lower annular passage 7 il having outer and inner walls respectively formed by the bottom hole and pump assemblies 2d and 22 and extending from within the sealing collar 55 upwardly through the lower pump housing tube 54 into the low-er intermediate sealing collar 5i?. The inlet passage means da further includes an upper annular passage 72 the lower end of which is connected to the upper end of the lower annular passage l by a bypass passage 74 formed in the lower intermediate sealing collar 5t?, the upper annular passage 72 having outer and inner walls respectively formed by the bottom hole and pump assemblies Ztl and 22 and extending upwardly from within the lower intermediate sealing collar Sil through the upper pump housing tube 43 into the upper intermediate sealing collar 4t2.

lt will be noted that, with the exception of the inlet passage 66 of the inlet passage means 54, all of the components or portions of the production fluid inlet passage means 64 and the production fluid outlet passage means 44, d6, 52 and 53 are located within the bottom hole assembly Ztl externally of the pump assembly 22 so that they do not occupy any space within the pump assembly which would tend to reduce the displacement thereof, which is an important feature of the invention. Since the inlet passage do is formed in the inlet plug 68 at the lower end of the pump assembly ZZ, it has no eifect on the displacement of the pump assembly.

Similar considerations are applicable to the handiing of the operating fluid under pressure for actuating the pump assembly 22 and the spent operating uid discharged by the pump assembly, the high pressure operaing lluid and the low pressure spent operating fluid being handled in passages within the bottom hole assembly Ztl* externally of the pump assembly 22 wherever necessary to avoid a tendency to reduce the displacement of ythe pump assembly with respect to the operating fluid. In this connection, it will be noted that the operating fluid exhaust passage means 33 is formed in the upper sealing collar 36 externally of the pump assembly 22. With this same objective inmind, the bottom hole assembly Zi provides an annular operating fluid passage 76 which eX- tends from within the upper sealing collar 36 downwardly through the motor housing tube it@ into the upper intermediate sealing collar 42, the outer and inner Walls of this annular passage also being formed by the bottom hole and pump assemblies 2t) and 22, respectively, so that such passage is also located entirely externally of the pump assembly. The function of the annular operation fluid passage 7 6 will be brought out hereinafter.

Considering the pump assembly 22 in detail now, it includes at its upper end a packer noseassembly 78 cornprising a tubular packer mandrel 8d having thereon downwardly facing packer cups 82 which make tiuid tight seals with the supply tubing 3d when liuid pressure is applied therebeneath, whereby the pump assembly may lbe moved upwardly through the supply tubing to the surface hydraulically in a manner to be described. rihe packer mandrel uit is provided therein with ports forming an operating tiuid intake 842 for admitting operating fluid under pressure from the supply tubing 30 into the pump assembly 22.

The lower end of the packer mandrel Si) is connected to an upper sealing adapter 86 which registers with the up er sealing collar 3d when the pump assembly 22 is in its operative position. The upper sealing adapter Se is provided therein with ports forming an operating uid exhaust S8 which communicates with the exhaust passage means 38 in the upper sealing collar 36 when the pump assembly 22 is in its operative position. The operating fluid exhaust Se and the exhaust passage means 38 are isolated by elastomeric annular seals 9G and 92 carried by the upper sealing adapter 86 respectively above and below the operating fluid exhaust 83 and engageable with the upper sealing collar 36.

Connected to the lower end of the upper sealing adapter 36 is a fluid operated engine or motor section 94 of the pump assembly ZZ, the lower end of the motor section being connected to an upper intermediate sealing adapted 96 which is disposed within the upper intermediate sealing collar d2 when the pump assembly 22 is in its operative position. The annular operating fluid passage 75 within the motor housing tube 4h encircles the motor section 94 of the pump assembly 22 and is isolated by the seal 2 on the upper sealing adapter 86 and by an elastomeric annular seal 93 on the sealing adapter 96 and engageable with the sealing collar 42.

'the fluid operated motor section 94 of the pump assembly 22 includes a motor cylinder litt) formed by a motor cylinder barrel or tube lill and having therein a motor piston N2 which is reciprocated in the motor cylinder by connecting the upper and lower ends of the motor cylinder first to the operating fluid intake and exhaust 8d and 83, respectively, and then to the operating fluid exhaust and intake 38 and 8d, respectively, in an alternating manner. In other words, the connections between the upper and lower ends of the motor cylinder lo!) and the operating iiuid intake and exhaust 84 and 8S are alternately reversed, thereby applying to the motor piston 02 an alternating uid pressure force diderential which reciprocates it in its cylinder.

lThe `foregoing effect is achieved by Ean engine or motor valve 1M, FIG. 2, forming part of the motor section 94 of the pump assembly 22 and communicating with the operating fluid intake and exhaust S4 and 88. The engine valve we is conventional and may, for example, be of the type disclosed in Patent No. 2,311,157, granted February 16, 1943 to Clarence I. Coberly. Consequently, it is unnecessary to consider the engine valve 104 in detail herein, it being sufficient -to point out that it includes a fluid operated valve member 106 slidable vertically in a valve body 108 and controlled by a valve rod 110 connected to the motor piston 102. The valve body 108 connects the upper end of the motor cylinder barrel 101 to the upper sealing adapter 86 as shown in FIG. 2, the lower end of the motor cylinder barrel being connected to the upper intermediate sealing adapter 96, as shown in FIG. 3.

The motor section 94 of the pump assembly 22 is provided with two operating fluid passage means 112 and 114 respectively connecting the engine valve 104 to the upper and lower ends of the motor cylinder 100, the two passage means mentioned providing the communication between the engine valve and the upper and lower ends of the motor cylinder which is necessary to permit the engine valve to apply to the motor piston 102 the alternating uid pressure force diierential discussed previously. As shown in FIG. 2, the operating fluid passage means 112 establishing communication between the engine valve 104 and the upper end of the motor cylinder 100 includes suitable passages, ports and the like in the engine valve body 108 and in a tubular fitting assembly 116 disposed in the upper end of the motor cylinder barrel 101 adjacent the engine valve 104. The passages, ports and the like forming the operating fluid passage means 112 are clearly shown in FIG. 2 of the drawings and it is therefore thought unnecessary to describe them in detail.

The operating uid passage means 114 connecting the engine valve 104 to the lower end of the -rnotor cylinder 100 includes the annular operating tiuid passage 76 described previously. The upper end of the annular passage 76 communicates with ports 118 which, in turn, communicate with the engine valve 104 through suitable passages, ports, and the like formed in the fitting assembly 116 and the engine valve body 118 and adequately illustrated in FIG. 2 of the drawings so that describing them in detail is unnecessary. The ports 118 are formed in the upper end of the barrel or tube 101 forming the motor cylinder 100 and are prevented from communicating with the upper end of the motor cylinder proper by the fitting assembly 116. The lower end of the annular passage 76 communicates with ports 120 formed in the lower end of the barrel 101 and communicating with the lower end of the motor cylinder 100 below the motor piston 102 through suitable ports, passages, and the like formed in the upper intermediate sealing adapter 96 and clearly illustrated in FIG. 3 of the drawings.

It will be noted that the portion of the operating Huid passage means 114 which `bypasses the motor cylinder 100 to connect the engine valve 104 to the lower end of the motor cylinder, viz., the annular operating fluid passage 76, is located entirely externally of the pump assembly 22 within the bottom hole assembly 20. Consequently, the annular operating fluid passage 76 takes up no space within the pump assembly 22 itself, whereby the diameter of the motor cylinder 100 may be a maximum, being less than the over-all diameter of the pump assembly only `by the amount necessary to provide the barrel or tube 101 forming the motor cylinder 100 with adequate Structural strength. Consequently, making the ybypass passage 76 an annular one encircling the exterior of the pump assembly 22 results in a motor section 94 having maximum displacement and producing maximum power for a given over-all diameter of the pump assembly, which are important features of the invention.

The pump means of the pump assembly 22 includes in the construction illustrated upper and lower doubleacting pump sections 122 and 124 respectively disposed in the upper and lower pump housing tubes 48 and 54 when the pump assembly 22 is in its operative position. The upper and lower pump sections 122 and 124 respectively include upper and lower pump cylinders 126 and 128 respectively formed by upper and lower pump cylinder barrels or tubes 130 and 132. Respectively reciprocable in the upper and lower pump cylinders 126 and 128 are upper and lower pump pistons 134 and 136, the upper pump piston 134 being connected to the motor piston 102 by a rod 13S, FIGS. 3 and 4, and the two pump pistons being interconnected by a rod 140, FIGS. 4 and 5. Connected to the lower pump piston 136 and extending downwardly therebelow into a `balance tube 142, FIGS. 5 and 6, is a lower rod 144. The cross sectional area of the lower rod 144 is the same as that of the valve rod 110, and the rods 110, 138, 140 and 144 and the pistons 102, 134 and 136 are `all tubular so that the uid pressure act ing downwardly on the valve rod is also present in the balance tube 142 to act upwardly on the lower rod 144. Thus, the piston and rod assembly is hydraulically `balanced with respect to the Huid pressure acting downwardly on the valve rod 110, which fluid pressure is the op` erating fluid pressure in the supply tubing 30, being applied to the upper end of the valve rod through the packer mandrel 80, an axial passage 146, FIG. 2, in the upper sealing adapter 86 and the interior ofthe engine valve member 106.

Considering the pump means of the pump assembly 22 in more detail, the upper pump cylinder barrel is connected to the lower end of the upper intermediate t sealing adapter 96, FIG. 3, and the lower end of this barrel is connected to the upper end of a lower intermediate sealing adapter 143, FIG. 4. The upper end of the lower pump cylinder barrel 132 is connected to the lower end of the lower intermediate sealing adapter 148, FIG. 4, and the lower end of the lower pump cylinder barrel is connected to a tting 150, as shown in FIG. 5. The balance tube 142 mentioned previously is connected to the lower end of the fitting and a barrel or tube 152 surrounding the balance tube 142 connects the fitting 150 to the lower sealing adapter 154, which is disposed within the lower sealing collar 55 when the pump assembly 22 is in its operative position. The inlet plug 63 at the lower end of the pump assembly is connected to the lower sealing adapter 154.

Since the upper and lower pump sections 122 and 124 are double acting as previously stated, each is provided with two vertically spaced production fluid inlets. The upper and lower production fluid inlets of the upper pump section 122 are designated by the numerals 156 and 158, respectively, and the upper and lower production fluid inlets of the lower pump section 124 are designated by the numerals and 162, respectively. The production fluid inlets 156 and 158 for the upper pump section 122 communicate with the upper annular passage 72 of the production fluid inlet passage means 64, while the production fluid inlets 160 and 162 of the lower pump section 124 communicate with the lower annular passage '70 of the production fluid inlet passage means 64. Since the upper and lower annular passages 70 and 72 are entirely external with respect to the pump assembly 22, they do not take up any of the cross sectional area thereof. Consequently, they do not restrict the diameters of the pump cylinders 126 and 128, these diameters, which are preferably equal, being less than the over-all diameter of the pump assembly by only the amounts necessary to provide the pump cylinder barrels 130 and 132 with the necessary structural strengths. Consequently, the pump sections 122 and 124 have the maximum possible displacements for a given over-all diameter of the pump assembly 22, which is an important feature.

The upper annular production inlet passage 72 is isolated, so that it communicates only with that portion of the exterior of the upper pump section 122 having the production fluid inlets 156 and 158 therein, by elastomeric annular seals 164 and 166 respectively carried by the upper and lower intermediate sealing adapters 96 and 148. Similarly, the lower annular production fluid inlet passage 70 is isolated, so that it communicates only with that portion of the exterior of the lower pump section 124 having the production fluid inlets 160 and 162 therespasso@ in, by elastomeric annular seals 16S and 170 respectively carried by the lower intermediate and the lower sealing adapters, 143 and i541.

As shown in FIG. 3, the upper production fluid inlet 156 of the upper pump section 122, which inlet is shown as comprising circumferentially spaced ports, is formed in the upper end of the upper pump cylinder barrel 13d and communicates with the upper end of the upper pump cylinder 126 through a suitable inlet check valve means 72 carried by the upper intermediate sealing adapter 96. The inlet check valve means 172 includes suitable passages, ports, and the like in the upper intermediate sealing adapter 96 which it is though unnecessary to describe specifically, these being clearly shown in FIG. 3 of the drawings. Similarly, the lower production iluid inlet 15S of the upper pump section 122 is formed in the lower end of the upper pump cylinder barrel 136` and communicates with the lower end of the upper pump cylinder 126 through a suitable inlet check valve means 174 carried by the lower intermediate sealing adapter 148, as shown in FIG. 4 of the drawings. Again similarly, the upper and lower production uid inlets 160 and 162 of the lower pump section 124 are formed in the upper and lower ends of the lower pump cylinder barrel 132, as shown in FIGS. 4 and 5, respectively, and respectively communicate with the upper and lower ends of the lower pump cylinder 128 through suitable upper and lower inlet check valve means 176 and 178 respectively carried by the lower intermediate sealing adapter 148 and the fitting 150.

The foregoing completes the description of the manner in which production fluid from the well is admitted into the upper and lower ends of the upper and lower pump sections i122 and 124, and the manner in which the production uid is discharged therefrom into the main outlet passage means 46 through the branch outlet passage means 44, 52 and 53 will now be described.

The upper intermediate sealing adapter 96 is provided between the seals 98 and 164 thereon withports forming a production uid outlet 18) for the upper end of the upper pump section 122, this outlet registering with kthe branch outlet passage means 44 when the pump assembly 22 is in its operative position in the bottom hole assembly 2l). As shown in FIG. 3 of the drawings, the upper intermediate sealing adapter 96 carries an outlet check valve means 182, through which production fluid discharged from the upper end of the upper pump cylinder 126 ows to the production tluid outlet 189 by way of suitable ports, passages, and the like in the sealing adapter in question, these being clearly shown in FIG. 3 so that a further description is unnecessary. Similarly, the branch outlet passage means ltd with which thetproduction fluid outlet 389' registers includes a collection of annular grooves, ports, und the like in the upper intermediate sealing collar 42 which are clearly shown in FlG. 3 so that a further description is not required.

Disposed between the seals E66 and ldd `on the lower intermediate sealing adapter 14d is a production fluid outlet l8r/4 comprising circumferentially spaced ports formed in the sealing adapter 14S and registering with the branch outlet passage means 52 in the lower intermediate sealing collar l when the pump assembly 22 is in its operative position. As shown in FlG. 4 o-f the drawings, the branch outlet passage means S2 comprises a collection or" grooves, ports, and the like in the lower intermediate sealing collar 5d which it is unnecessary to escribe specitoally. The production fluid outlet 184 serves the lower end of the upper pump sectionlZZ and the upper end of the lower pump section 124, the production fluid outlet ldd communicating with the lower end of the upper pump cylinder R26 through an outlet check valve means 186 and communicating with the upper end of the lower pump cylinder 32S through an outlet check valve means 13S, the two outlet check valve means just mentioned being carried by the lower intermediate seall@ ing adapter ldd. Communication between the lower end `of the upper pump cylinder lid and the production iiuid outlet l34 through the outlet check valve means ld and communication between the upper end of the lower pump cylinder ldd and the production-duid outlet ld through the outlet check valve means ldd are established by suitable ports, passages, and the like in the lower intermediate sealing adapter these being clearly shown in PEG. 4 of the drawings so that a further description is not needed. Similarly, the branch outlet passage means 52 with which the production uid outlet ldd communicates when the pump assembly 22 is in its operative position is formed by suitable grooves, ports, and the like in the lower intermediate sealing collar 50 which are also clearly shown in FlG. 4 so that they need not be de- `scribed in detail.

The lower end of the lower pump section 124 discharges production fluid through an outlet check valve means 19t), FG. 5, carried by the iitting i542, this fitting being provided with suitable ports, passages, and the like which, as shown in FlG. 5, connect the lower end of the lower pump cylinder llt? to the annular space between the balance tube 142, and the tube l52 which connects the fitting 15d to the lower sealing adapter 154. As shown in FlG. 6, the lower sealing adapter 154 is provided with suitable passages, ports, and the like which f into the main outlet passage means 46.

Since the main outlet passage means 46 is located in the bottom ho-le assembly Zt? externally of the pump assembly Z2, being located alongside the pump assembly and communicating with the production duid outlets ld, ld and H2 through the branch outlet passage means 44, 52 and 58, respectively, it takes up none o-f the cross sectional area of the pump assembly. Consequently, the external location of the main outlet passage means 46 permits maximum displacement for the motor section 94! and the pump sections l2@ and ll of the pump assembly 22.

Summarizing, it will thus be apparent that the present invention achieves its primary objective of maximizing displacement by locating all of the various passage means for the operating fluid under pressure, the spent operating fluid, the production l'iuid admitted to the pump sections 122 and 124, and the production iluid discharged by such pump sections, externally of the pump assembly 2Q. in the vicinities of the motor cylinder llltl' and the pump cylinders M6 and l2@ so that the diameters of these cylinders may be maximized, being less than the over-all diameter of the pump assembly only by amounts necessary to achieve adequate structural strengths for the cylinders. This means maximum displacement for a given over-all diameter of the pump assembly 22, or, looked at from another point of view, it means a minimum overall diameter for the pump assembly for a given displacement. Not only does this result in a lower cost for the pump assembly Z2 itself, but, more important, it means a smaller diameter for the supply tubing 3d through which the pump assembly is run for a given displacement. Being able to utilize a smaller supply tubing 3l) f-or a given displacement represents a considerable saving when it is kept in mind that the supply tubing may be many thousands of feet in length.

rl`he pump assembly 22, is run into and out of the well hydraulically in the usual manner for pump assemblies of this type. Brietiy, the pump assembly 22 is run in from the surface into its oper-attive position in the bottom hole assembly Ztl by introducing fluid into thesupply tubing 11 30 above the pump assembly at a pressure suillcient to move the pump assembly downwardly into its operative position. To run the pump assembly 22 out, tluid is introduced into the upper end of the production tubing 34, whereby the fluid in the production tubing and in the main outlet passage means 46 enters the pump-assembly rhousing provided by the bottom hole assembly 20 below 22 unseats from the standing valve assembly 62, whereupon the standing valve closes, the upward pressure ap- Yplied to the production tubing 34 acts on the entire cross sectional area of the pump assembly to move it upwardly. Until such time as the lowermost seal 170 disengages the lower sealing collar S, it prevents bypassing of the fluid introduced through the production tubing 34 past the pump assembly. Thereafter, the packer cups S2 at the upper end of the pump assembly 22 prevent bypassing so that the pump assembly is hydraulically lifted to .the surface.

Considering now another important feature of the present invention, each of the various external annular seals 90, 92, 98, 164, 166, 168 and 170 carried by the pump assembly 22 is loaded in the vertical or axial direction when the pump assembly is in its operative position to such an extent that it will not expand and contract excessively as the pressure of one or the other of the fluids which it separates decreases and increases, respectively. In order to minimize such expansion and contraction of the seals in question, they are pressurized or loaded to en extent of at least the same order of magnitude as the differences between the pressures of the fluids which they separate, and preferably higher. The resultant minimizing of expansion and contraction of each of the seals mentioned as the pressure of one or the other of the .fluids separated thereby decreases and increases minimizes internal friction within the seal, and thus prevents the heat generation which such internal friction would produce, the net effect being a very marked increase in the service life of the seal. Without such loading or pressurization, the external seals on the pump assembly which separate fluids having variable pressure differentials therebetween would burn out in very short periods of time from the heat generated by internal friction as they expand and contract.

Further, since the foregoing loading or pressurization of each of the seals 90, 92, 98, 164, 166, 16S and 170 is in the axial direction, it results in squeezing such seal outwardly into sealing engagement with the corresponding component of the bottom hole assembly 20 only when the pump assembly 22 is in its operative position. Thus, it is not necessary to subject the seals in question to "initial squeezes, which means that their external diameters are less than the external diameters of the sealing adapters of the pump assembly as the latter is run into or out of the well. Consequently, the external seals on the pump assembly cannot be abraded by the supply tubing 30 and the bottom hole assembly 20 as the pump assembly is run in or out, which is another important feature.

The various external seals 90, 92, 98, 164, 166, 168 and 170 are pressurized or loaded in similar fashions so that it is necessary to consider how this is accomplished in connection with only a couple of the seals, c g., the seals 98 and 164, for purposes of illustration. The manners in which the seals 98 and 164 are pressurized when the pump assembly 22 is in its operative position are shown in FIGS. l() and 1l, respectively, these figures duplicating portions of FIG. 3 on an enlarged scale.

Considering the seal 9S first, it encircles a reduced diameter portion 194 of the upper intermediate sealing adapter 96 and is engageable with a liner 196 forming part of the upper intermediate sealing collar 42. The seal 98 is disposed between a lower rigid sleeve 198, which encircles the reduced diameter portion 194 of .the sealing adapter 96 and which is engageable with an -annular shoulder 200 thereon, and an upper rigid, differential area sleeve 202 which is axially slidablc on the reduced diameter portion 194 of the sealing adapter 96 and on a further reduced diameter portion 204 thereof, an O-ring 206 maintaining a fluid tight seal between the sleeve 202 and the portion 204 of the sealing adapter 96. The sleeve 202 has a small-area lower end 208 engageable with the seal 9S and a large-area upper end 210, this sleeve also having an internal annular surface 212 the area of which is equal to the difference between ythe cross sectional areas of the portions 194 and 204 of the sealing adapter 96, and thus to the difference between the areas of the upper and lower ends 210 and 208 of the sleeve.

The upper end 210 of the sleeve 202 is exposed to the pressure in the annular operating fluid passage 76 Ithrough the slight annular clearance, not shown, which is necessarily present between the motor cylinder barrel 101 and the liner 196 of the upper intermediate sealing collar 42, the pressure in the annular operating fluid passage 76 being alternately the operating fluid pressure in lthe supply tubing 30 and the spent operating uid pressure in the return tubing 32. The annular surface 212 of the sleeve 202 is exposed to the production iluid inlet pressure through one or more ports and passages 214 and 216 in the upper intermediate sealing adapter 96, the passage or passages 216 communicating with the production fluid inlet 156 in the manner shown in FIG. v3 of the drawings.

It will be apparent from the foregoing that the sleeve 202 is a differential area sleeve having either the pressure of the operating fluid in the supply tubing 30, or thc pressure of the spent operating iluid in the return tubing 32, applied to the upper end 210 thereof and having the much lower production iluid inlet pressure applied to the annular surface 212 thereof. The pressures acting on the upper end 210 of the sleeve 202 and the pressure acting on the annular surface 212 thereof produce an axial force which axially compresses the seal 98 and which is equal to the area of the annular surface 212 multiplied by the difference between the production iluid inlet pressure and either the pressure of the operating fluid in the supply tubing 30, or the pressure of the spent operating fluid in the return tubing 32. In either event, the pressure applied to the seal 98 exceeds the difference between the pressures which this seal separates, the pressure below the seal 98 being the pressure of the production iluid column in the production tubing 34, and the pressure above this seal being either the pressure of the spent operating tluid column in the return tubing 32, which is the same as the pressure of the production fluid column in the production tubing if the densities of the operating and production fluids are the same, or the pressure of the operating fluid in the supply tubing 30. Consequently, as the pressure above the seal 98 alternates between the pressure in the supply tubing 30 and the pressure of the spent operating fluid column in the return tubing 32, the seal cannot expand and contract excessively and thus cannot generate excessive heat by internal friction so that its service life is materially extended, which is an important feature.

Referring to FIG. 1l of the drawings, encircling the sealing adapter 96 is a band 220 which, in turn, is encircled by the seal 164, the latter being engagcable with the liner 196 of the sealing collar 42. The seal 164 is disposed between a sleeve 222, which encircles the band 220 and which is seated on the upper end of the upper pump cylinder barrel 130, and a differential area sleeve 224 slidably engaging the band 220 and the sealing adapter 96. The sleeve 224 has a small-area lower end production fluid inlet pressure.

226 engaging the seal 164 and a large-area upper area 22S exposed to the production liuid discharge pressure in the branch outlet passage means 44, this sleeve being sealed internally relative to the sealing adapter 96 by an O-ring 23o. The differential area sleeve 22d is also provided with an internal annular ysurface 232 facing in the opposite direction from the upper end 238 thereof and having an area equal to the difference between the areas of the upper and lower ends 22S and 226. As will be apparent, the band 22h effectively increases the diameter of a portion of the sealing adapter 96 to provide the differential area between the upper and lower ends 223 and 226 of the sleeve 224.

As previously stated, the upper end 228 of the sleeve 224 is exposed to the production fluid outlet pressure in the branch outlet passage means 44. The annular surface 232 is exposed to the production fluid inlet pressure in the `upper annular inlet passage 72, as will be apparent from FIG. 3, through clearances, not shown, inherently present between the liner 196 and the upper pump cylinder barrel 130, between the upper pump cylinder barrel and the sleeve 222 and the band 220 and between the `sealing adapter 96 and-the band 229. Consequently, the

production iiuid discharge pressure acting on the upper end 223 of the sleeve 224 and the production fluid inlet pressure acting on the'annular surface 232 thereof result in the application of a pressure to the seal ldd equal to the area of the annular surface 232 multiplied by the diiferencebe'tween'the production fluid discharge pressure and the production fluid inlet pressure. Thus, the seal 164 is subjected to a pressure at least equal to the difference between the pressures ofthe iiuids which it separates.

The seals 166, 168 and 170 are pressurized in much the same manner as the seal 164, utilizing the difference between the production fluid discharge pressure and the Consequently, a further description is unnecessary.

The seal 90 at the upper end of the pump assembly 22 is pressurized in much the same manner as the seal 98, except that the difference between the operating fluid pressure in the supply tubing and the pressure ofthe spent operating uid in the return tubing 32 is utilized, as will be apparent from FIG. 2 of the drawings. Briey, the seal 9i) is pressurized by a differential area sleeve 234 having its upper end 236 exposed to the operating uid pressure in the supply tubing 3o and having a smaller, downwardly facing annular surface 238 exposed to the return fluid pressure in the operating uid exhaust di; through one or more ports and passages `249.9 and 242. The action of the sleeve 23d on the seal 90 is very similar to that of the sleeve 202 on the seal 93 so that a further description is not required. The pressure applied to the seal 90 by the sleeve 234 in this fashion is transmitted to the seal 92 mechanically by sleeves 244, 246 and 243 slidable on the upper sealing adapter 86, the sleeve 245 having the operating fluid exhaust d3 formed therein.

Thus, when the pump assembly 22 is in its operative position and is in operation, all of the external seals thereon are pressurized to urge them into sealing engagement with the corresponding components of the bottom hole assembly 2d, and to prevent them from expanding and contracting so that the resultant detrimental effect of heat generation due to internal friction is avoided. Further, al1 4of the seals which separate the clean operating uid from the possibly contaminated production fluid, viz., the seals 98, 64, 16d, le@ and tl, are pressurized when the pump assembly 22 is in its operative position with the standing valve 62 open, even if the pump is shut down. Thus, the operating fluid cannot become contaminated, which is an important feature. When the pump assembly 22 is being run in or out, the external seals are retracted into the grooves formed by the sleeves which receive them therebetween so that the seals cannot be abraded by contact with the bottom hole assembly 2h, or the supply tubing 30.

Preferably, the annular seals 9i), 92, 93, ldd, loo, L68 and t7@ have steel cores to insure outside diameter accuracy and to resist blowing out of their grooves.

Turning now to another important feature of the present invention, the main outlet passage means @iti paralleling the pump assembly 22 includes a pipe 25d interconnecting the upper and lower intermediate sealing collars ft2 and Sti and a pipe 252 interconnecting the -lower intermediate sealing collar dit and tie bottom shoe 5d. nterconnecting the upper and lower intermediate sealing collars 2 and 5t? by means of the upper pump housing tube d3 and the pipe 25d, and interconnecting the lower intermediate sealing collar 50 and the bottom shoe 56 by means of the lower pump housing tube 54 and the pipe 252, presents certain problems which are considered hereinafter and which the present invention overcomes in the manner set forth hereinafter. For convenience, the consideration of this aspect of the invention will be restricted to interconnecting the lower intermediate sealing collar Si? and the bottom shoe 56 with the lower pump housing tube 5ft and the pipe 252, with the understanding that the discussion also applies to interconnecting other components of the bottom hole assembly Referring to FIGS. 4, 5 and 6 of the drawings, it will be noted that the pump housing tube 54 is threaded into the lower Vsealing collar 55 by means of ordinary tapered pipe threads. Consequently, once the lower end of the pump housing tube 5d is threaded all the way into the sealing collar $5, no further relative rotation of these parts is possible. However, it is necessary to provide relatively unrestricted rotation between the bottom shoe S6 and the seating collar Sii at some point to permit alignment of the portions of' the sealing collar Sti and the bottom shoe 56 into which the parallel pipe 25'2 is threaded in the manner shown in FiGS. 4 to 6 of the drawings, and to space the sealing collar Sit and the bottom shoe accurately. For this purpose, the upper end of the pump housing Sdis threaded into the sealing collar 5t) with extended, i.e., straight threads and is secured by a lock nut 255, FIG. 4, threaded on the pump housing tube and seated against the sealing collar 56. With this construction the sealing collar Sti may be rotated relative to the pump housing tube 5.4i to align the portions of the seating collar 5d and the bottom shoe 56 into which the pipe 252 is threaded. Once this is done, the lock nut 256 is tightened to maintain the desired relative angular positions, and the desired axial spacing, of the sealing collar Sti and the bottom shoe 55.

As will be apparent, since relative rotation between the bottom shoe 56 and the sealing collar 50 must occur while the desired angular positions and axial spacing of these components are being established, connecting the parallel pipe to the seal'ng collar 5d and the bottom shoe 55, or to at least one of them, must be done later. Also, there must be provision for axial movement of the pipe 252 relative to one or the other of the scaling collar 5t? and the bottom shoe 56 to permit threaded connections of the pipe 252 to both of these components.

lThe present invention solves the foregoing problems by dividing the pipe 252 into an upper section 25S and a lower section 2661 with a telescoping connection or siip joint 2d?. therebetween. Referring to FiG. 5 of the drawings, threaded onto the upper end of the lower pipe section Zed is a coupling 26d having a stem 2de whichis slidable in the upper pipe section and which carries an G-'ring to provide' a fluid tight seal therebetween. A gland nut 27d is threaded onto the coupling 264 and is provided with an internal annular iiange 272 engageable with an external annuiar iiange 274i on the upper pipe section 253.

With the foregoing construction, after the sealing collar Sti and the bottom shoe 5d have been locked in their proper relative positions, the telescoping connection 262 is contracted sufficiently to permit threading the upper and iower pipe sec-tions 25S `and 260 into the sealing collar 59 and the bottom shoe 56, respectively, the telescopic connection extending as this is done. Alternatively, one of the pipe sections 258 and Zeil is initially threaded into the corresponding component 56 or 56 of the bottom hole assembly 2i) and the proper relative positions of the sealing collar 56 and the bottom shoe 56 are then established with the telescopic connection 262 contracted to permit the pipe section 25S to clear the sealing collar 5), or the pipe section 260 to clear the bottom shoe 56. Thereafter, if the pipe section 258 was initially threaded into the sealing collar 59, the pipe section 266 is threaded into the bottom shoe 56, the telescopic connection 262 extending as this is done. In either case, once the pipe sections 258 and 260 are tightly threaded into the sealing collar Sti and the bottom shoe 56 by means of the tapered pipe threads shown, the gland nut 273 is tightened to complete the installation. Thus, the telescopic connection 262 between the pipe sections 253 and 26? provides a simple means of connecting the pipe 252 to the sealing collar 50 and the bottom shoe 56 after the relative positions of these components of the bottom hole assembly 20 have been established. Also, the gland nut 270 is tightened suliiciently to tension the pipe sections 258 and 26th to the extent necessary to prevent bowing of the pump housing tube 54 by the bending moment produced by the column pressure within the pipe 252 acting on the bottom shoe 56, which is an important feature.

Although exemplary embodiments of the present invention have been disclosed herein for purposes of illustration, it will be understood that various changes, modifications and substitutions may be incorporated in such embodiments without .departing from the spirit of the invention as dened by the claims which follow.

What is claimed is:

l. In a uid operated pump system for a well, the combination of: an elongated pump assembly of the reciprocating type including fluid operated motor means and including pump means operated by said motor means, said pump means having two vertically spaced production fluid inlets for production iluid from the well; and a bottom hole assembly providing 'housing means for housina said pump assembly in an operative position therein and providing passage means externally of said pump assembly for interconnecting said production iluid inlets in fluid communication when said pump assembly is in said operative position in said housing means, said housing means including a sealing collar and said pump assembly including a sealing adapter located between said production fluid inlets and having thereon sealing means engageable with said sealing collar when said pump assembly is in said operative position, said passage means including two vertically spaced, annular passages encircling said pump assembly respectively above and below said sealing collar and said sealing adapter when said pump assembly is in `said operative position and respectively communicating with said production fluid inlets, each of said annular passages having inner and outer walls respectively dened by said pump assembly and said housing means when said pump assembly is in said operative position, said sealing collar having therein a bypass passage which forms part of said passage means and which interconnects the lower end of the uppermost of said annular passages and the upper end of the lowermost of said annular passages, said bypass passage being located alongside and spaced from said pump assembly when the latter is in said operative position.

2. A pump system according to claim 1 wherein said pump means includes two pump sections separated by said sealing adapter and respectively having said production lluid inlets therein.

3. A pump system according to claim 1 wherein said pump means includes two pump sections separated by said sealing adapter and respectively having said production fluid inlets therein, said pump sections being double 16 acting and respectively having second production tluid inlets respectively spaced vertically from the production fluid inlets rst mentioned and respectively communicating with said annular passages when said pump assembly is in said operative position.

4. in a fluid operated pump system for a well, the combination of: an elongated pump assembly of the reciprocating type including a fluid operated motor section and including two pump sections all structurally interconnected in tandem, said motor section including a motor piston and said pump sections respectively includ,- ing pump pistons connected to each other and to said motor piston, said pump assembly including an upper sealing adapter at the upper end of said motor section, an upper intermediate sealing adapter intermediate said motor section and the uppermost of said pump sections, a lower intermediate sealing adapter between said pump sections, and a lower sealing adapter at the lower end of the lowermost of said pump sections, each of said sealing adapters -having external sealing means thereon; and a bottom hole assembly providing housing means for housing said pump assembly in an operative position therein, said housing means including upper, upper in termediate, lower intermediate and lower sealing collars respectively engageable by said sealing means on said upper, upper intermediate, lower intermediate and lower :sealing adapters when said pump assembly is in said operative position.

5. In a iluid operated pump system for a well, the combination of: an elongated pump assembly of the reciprocating type including a iluid operated motor section and including two pump sections all structurally interconnected in tandem, said motor section including a lmotor piston and said pump sections respectively including pump pistons connected to eaoh other and to said rnotor piston, said pump assembly including an upper sealing adapter at the upper end of said motor section, an upper intermediate sealing adapter intermediate said motor section and the uppermost of said pump sections, a lower intermediate sealing adapter between said pump sections, and a lower sealing adapter at the lower end of the lowermost of said pump sections, each of said sealing adapters having external sealing means thereon, said pump sections respectively having production iluid inlets for production lluid from the well and respectively hav- ,ing production iluid outlets for production iluid discharged thereby; and a bottom hole assembly providing housing means for housing said pump assembly in an operative position therein, said housing means including upper, upper intermediate, lower intermediate and lower sealing collars respectively engageable by said sealing means on said upper, upper intermediate, lower intermediate and lower sealing adapters when said pump assembly is in said operative position, said bottom hole assembly providing production fluid inlet passage means and production iluid outlet passage means externally of said pump assembly for interconnecting said production fluid inlets in fluid communication and for interconnecting said production fluid outlets in uid communication, respectively, when said pump assembly is in said operative position in said housing means.

6. In a fluid operated pump system for a well, the combination of: an elongated pump assembly of the reciprocating type including a iluid operated motor section and including two pump sections all structurally interconnected in tandem, said motor section including a motor piston and said pump sections respectively including pump pistons connected to eachother and to said motor piston, said pump assembly including an upper sealing adapter at the upper end of said motor section, an upper intermediate sealing adapter intermediate said motor section and the uppermost of said pump sections, a lower intermediate sealing adapter between said pump sections, and a lower ser-.ling adapter at the lower end of the lowermost of said pump sections, each of said sealing adapters having external sealing means thereon, said pump sections respectively having production iiuid inlets for production uid from the well and respectively having production uid outlets for production huid discharged thereby; and a bottom hole assembly providing housing means for housing said pump assembly in an operative position therein, said housing means including upper, upper intermediate, lower intermediate and lower sealing collers respectively engageable by said sealing means on said upper, upper intermediate, lower intermediate and lower sealing adapters when said pump assembly is in said operative position, said bottom hole assembly providing production i'luid inlet passage means and production fluid outlet passage means externally of said pump assembly for interconnecting said production iluid inlets in fluid communication and for interconnecting said production uid outlets in fluid communication, respectively, when said pump assembly is in said operative position in said housing means, said production uid inlet passage means includingy two annular passages respectively communicating with said production fluid inlets and respectively located between said upper and lower intermediate sealing adapters and collars and between said lower intermediate and lower sealing collars and adapters, each of said annular passages having inner and outer walls respectively -dened by said pump assembly and said housing means when said pump assembly is in said operative position.

7. in a fluid operated pump system for a well, the cornbination of: an elongated pump assembly orf the reciprocating type including tuid operated motor means and including pump means operated by said motor means, said pump means having two vertically spaced production uid inlets for production fluid from the well and two vertically spaced production iluid outlets for production duid discharged by said pump means; a bottom hole assembly providing housing means for housing said pump assembly in an operative position therein and providing production inlet passage means and production outlet passage means externally of said pump assembly for interconnecting said production fluid inlets in iluid communication and for interconnecting said production fluid outlets in iiuid communication, respectively, when said pump assembly is in said operative position in said housing means; and means for preventing fluid communication between said production tluid inlets and said production fluid outlets when said pump assembly is in said operative position, including at least one sealing adapter on said pump assembly, at least one sealing collar on said housing means, and at least one elastomeric annular seal encircling and carried by said sealing adapter and engageable with the interior of said sealing collar when said pump assembly is in said operative position.

8. In a fluid operated pump system for a well, the combination of: an elongated pump assembly o1 the reciproeating type including :duid operated motor means and including pump means operated by said motor means, said motor means having two vertically spaced operating uid ports communicating with the exterior of said pump assembly; and a bottom hole assembly providing housing means for housing said pump assembly in an operative position therein and providing passage means externally of said pump assembly for interconnecting said operating 18 fluid ports in fluid communication when said pump assembly is in said operative position in said housing means, said passage means including an annular passage encircling said purnp assembly externally thereof and having inner and outer walls respectively defined by said ump assembly and said housing means when said pump assembly is in said operative position.

9. In a iluid operated pump system for a well, the combination of: an elongated pump assembly of the re ciprocating type including iiuid operated motor means and including pump means operated by said motor means, said motor means having two vertically spaced operating fluid ports communicating with the exterior of said pump assembly and said pump means having `two vertically spaced production huid ports communicating with the exterior of said pump assembly; and a bottom hole assembly providing housing means for housing said pump assembly in an operative position .therein and providing two passage means externally of said pump assembly rfor interconnecting said operating -uid ports in fiuid com munieation and for interconnecting said production uid ports in tluid communication, respectively, when said pump assembly is in said operative position in said housing means, said passage means respectively including annular passages encircling said pump assembly externally thereof and each having inner and outer walls respectively dened -by said pump assembly and said housing means when said pump assembly is in said operation position.

`lO. In a fluid operated bottom hole pump assembly, the combination of: a uid operated pump including an engine barrel providing an engine cylinder having an engine piston ltherein, a pump barrel providing a pump cylinder having a pump piston therein, and a piston rod connecting said engine and pump pistons; a tubular housing to receive said pump; means, including engine valve means and passage means, :for connecting opposite ends of `said engine cylinder alternately to operating pressure and exhaust pressure, said passage means being annular and being located externally of said engine barrel between said engine barrel and said housing and interconnecting vertically spaced, external, operating uid ports in said engine barrel; and another passage means for connecting opposite ends of said pump cylinder alternately to well pressure and discharge pressure, said other passage means being annular and being located externally of said pump barrel between said pump barrel `and said housing and interconnecting vertically spaced, external, production fluid ports lin said pump barrel.

References Cited in the file of this patent UNITED STATES PATENTS :1,333,342 Robertson et al. Mar. 9, 1920 1,851,801 Boone Mar. 29, 1932 2,162,748 Richards June 20, 1939 2,214,343 overall sept. 10, 194e 2,533,097 Dale Dec. 5, 1950 2,605,712 Davis Aug. 5, 1952 2,628,563 Coberly Feb. 17, 1953 2,653,545 Dempsey Sept. 29, 1953 2,712,458 tipson Ju1y 5, 1955 2,780,171 EHeddy Feb. 5, 1957 2,899,218 Creighton Aug. 1l, 1959 2,951,445 Calvert Sept. 6, 1960 

1. IN A FLUID OPERATED PUMP SYSTEM FOR A WELL, THE COMBINATION OF: AN ELONGATED PUMP ASSEMBLY OF THE RECIPROCATING TYPE INCLUDING FLUID OPERATED MOTOR MEANS AND INCLUDING PUMP MEANS OPERATED BY SAID MOTOR MEANS, SAID PUMP MEANS HAVING TWO VERTICALLY SPACED PRODUCTION FLUID INLETS FOR PRODUCTION FLUID FROM THE WELL; AND A BOTTOM HOLE ASSEMBLY PROVIDING HOUSING MEANS FOR HOUSING SAID PUMP ASSEMBLY IN AN OPERATIVE POSITION THEREIN AND PROVIDING PASSAGE MEANS EXTERNALLY OF SAID PUMP ASSEMBLY FOR INTERCONNECTING SAID PRODUCTION FLUID INLETS IN FLUID COMMUNICATION WHEN SAID PUMP ASSEMBLY IS IN SAID OPERATIVE POSITION IN SAID HOUSING MEANS, SAID HOUSING MEANS INCLUDING A SEALING COLLAR AND SAID PUMP ASSEMBLY INCLUDING A SEALING ADAPTER LOCATED BETWEEN SAID PRODUCTION FLUID INLETS AND HAVING THEREON SEALING MEANS ENGAGEABLE WITH SAID SEALING COLLAR WHEN SAID PUMP ASSEMBLY IS IN SAID OPERATIVE POSITION, SAID PASSAGE MEANS INCLUDING TWO VERTICALLY SPACED, ANNULAR PASSAGES ENCIRCLING SAID PUMP ASSEMBLY RESPECTIVELY ABOVE AND BELOW SAID SEALING COLLAR AND SAID SEALING ADAPTER WHEN SAID PUMP ASSEMBLY IS IN SAID OPERATIVE POSITION AND RESPECTIVELY COMMUNICATING WITH SAID PRODUCTION FLUID INLETS, EACH OF SAID ANNULAR PASSAGES HAVING INNER AND OUTER WALLS RESPECTIVELY DEFINED BY SAID PUMP ASSEMBLY AND SAID HOUSING MEANS WHEN SAID PUMP ASSEMBLY IS IN SAID OPERATIVE POSITION, SAID SEALING COLLAR HAVING THEREIN A BYPASS PASSAGE WHICH FORMS PART OF SAID PASSAGE MEANS AND WHICH INTERCONNECTS THE LOWER END OF THE UPPERMOST OF SAID ANNULAR PASSAGES AND THE UPPER END OF THE LOWERMOST OF SAID ANNULAR PASSAGES, SAID BYPASS PASSAGE BEING LOCATED ALONGSIDE AND SPACED FROM SAID PUMP ASSEMBLY WHEN THE LATTER IS IN SAID OPERATIVE POSITION. 